Cardiovascular training is a foundation of your fitness program and one of the four basic elements of fitness. Cardio-training, also referred to as aerobics, is your key to successful weight management. Cardio-conditioning exercises burn the most calories, lower your body fat levels, and help you to effectively manage your weight. Having a strong and healthy cardiorespiratory system also reduces your risk of heart disease. This chapter gives you insight into what aerobic exercise is, why it's beneficial, and how much and how hard you need to work to get results.